Design, Fabrication, and Evaluation of a Cow Dung Dewatering Machine for Small Farms

Abstract

Smallholder dairy farms face persistent challenges in managing high-moisture cow dung, which hampers its reuse in composting, biogas generation, and nutrient recycling. This study presents the design and development of a screw press-based cow dung dewatering machine tailored for decentralized applications. The system integrates a 3 HP (2.24 kW) single-phase motor, a 1:40 worm gearbox, and a constant-pitch auger to achieve solid–liquid separation under constrained operational settings. Machine components including shaft, pressure plate, and filter mesh were optimized through iterative prototyping, engineering calculations, and factorial experiments. Filtration trials were conducted using three slurry feed ratios (0.5:1, 1:1, 2:1) and three filter mesh sizes (0.5 mm, 1.0 mm, 1.5 mm). Results revealed that the 1:1 dung-to-water ratio combined with a 0.5 mm filter mesh delivered the most effective performance. The machine offers a reliable and field-serviceable solution for managing semi-solid organic waste in smallholder farms, promoting sustainable manure handling practices.